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Chromium trioxide

Chromium trioxide
IUPAC name Chromium(VI) oxide
Other names Chromium trioxide
CAS number 1333-82-0
RTECS number GB6650000
Molecular formula CrO3
Molar mass 99.994 g/mol
Appearance Dark red solid
Density 2.70 g/cm3, solid
Melting point

197 °C

Boiling point

250 °C, decomposes

Solubility in water 63 g/100 mL
EU classification Oxidizer (O), very toxic (T+), dangerous for the environment (N)
NFPA 704
R-phrases R45 R46 R9 R24/25 R26 R35 R42/43 R48/23 R62 R50/53
S-phrases S53 S45 S60 S61
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

The acid anhydride of chromic acid is chromium trioxide or chromium(VI) oxide; industrially, this compound is sometimes sold as "chromic acid".[1] This compound is an intensely-colored dark red/orange brown, water-soluble, granular solid which is stable by itself, but is a strong oxidant which will react when mixed with many things that can be oxidized. Ethanol, for example, will ignite on contact with it.



Chromium trioxide is produced commercially by the reaction of sodium dichromate with concentrated sulfuric acid.[1]

Structure and chemistry

Chromium trioxide consists of chains of tetrahedrally coordinated chromium atoms that share vertices. Each chromium atom therefore has "half share of two oxygen atoms" and two oxygen atoms that are not shared, giving an overall stoichiometry of 1:3.[2]
Chromium trioxide decomposes above 197°C liberating oxygen eventually giving Cr2O3. The reaction of chromium trioxide with organic substances is potentially explosive. In spite of this, CrO3 is used in organic chemistry as an oxidant, often dissolved in acetic acid,[2] or acetone in the case of the Jones oxidation.


Chromium trioxide is highly toxic, corrosive, and carcinogenic.[3]


  1. ^ a b Chromium Trioxide. Chemicalland21.
  2. ^ a b Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999). Advanced Inorganic Chemistry (6th Edn.) New York:Wiley-Interscience. ISBN 0-471-19957-5.
  3. ^ Chromium Trioxide (MSDS). J. T. Baker. Retrieved on 2007-09-13.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Chromium_trioxide". A list of authors is available in Wikipedia.
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